ISSN:
1572-8927
Keywords:
2D and14N nmr
;
rotational correlation times
;
aqueous mixtures
;
H bonding and hydrophobic effects
;
formamide
;
N-methylformamide
;
N,N-dimethylformamide
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Nuclear magnetic relaxation rates of2D and14N in binary aqueous mixtures of formamide,N-methylformamide (NMF), andN,N-dimethylformamide (DMF) are reported as a function of the mixture composition. From these intramolecular quadrupolar relaxation data separate rotational correlation times for the two components of the mixture can be determined. The relative variation of the single correlation time as a function of the composition is interpreted in terms of structural changes caused by hydrogen bonding and hydrophobic effects. The results also clearly reflect the expected characteristic variation of these effects on the rotational molecular motions in going from formamide to NMF and DMF. The maximum correlation time retardation of DMF in the aqueous mixture is compared with those of other hydrophobic solvents. A correlation between this maximum retardation and the excess enthalpy of mixing of hydrophobic solvents in aqueous solution can be established graphically.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00652019
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